In general, a light emitting element used for a light emitting device includes an inorganic LED (Light Emitting Diode), an organic LED, a laser diode, an inorganic thick film electroluminescence sheet or an inorganic thin film electroluminescence parts and the like. Among others, LED stands out in characteristics such as long life, space-saving, good resistance to impact shock, and further, capable of emitting a light in a narrow spectral band.
A number of luminous colors, i.e. a number of luminous colors in a particularly wide spectral band cannot be realized or can be realized only in an inefficient manner by light emission inherent to an active semiconductor material in LED. Especially, such tendency is remarkable in case of white light emission.
According to the well-known technical level, a luminous color which cannot be essentially realized is attained by a wavelength conversion technique. The wavelength conversion technique is essentially based on the following principle. Namely, at least one phosphor is placed on an LED, and the light emitted from the LED is absorbed by the phosphor to emit a light having a wavelength different from that of the light absorbed. In other words, a light emitted is absorbed by an LED, and then, a photoluminescence light is radiated with another luminous color.
As a light emitting device emitting a light of white color based on the principle as described above, a white LED lamp wherein a light emitted from a purple LED is wavelength-converted by phosphors of respective colors of red/green/blue (hereinafter referred to as “red/green/blue phosphors in case of expressing collectively) which are in practical use at present, to emit a light is well known. Respective components of the red/green/blue phosphors are as follows.
Red phosphor: La2O2S:Eu, Sm (YOS:Eu)
Green phosphor: 3 (Ba, Mg, Eu, Mu) O.8Al2O3(BAM:Eu, Mn)
Blue phosphor: (Sr, Ca, Ba, Eu)10 (PO4)6.Cl2 
However, there is such a problem that color rendering properties are low in a conventional white light emitting device (white LED lamp).
FIG. 1 is a spectral diagram indicating emission intensity of a conventional white LED lamp. As shown in the figure, since there is scarcely a yellow component having a wavelength of 560 to 590 nm, an average color rendering evaluation number Ra of the white LED lamp is as low as about 50 to 60. In a usual fluorescent lamp, an average color rendering evaluation number Ra is about 80 to 90, and ideal is 100.
On the other hand, in a white light emitting device wherein white color is realized by a combination of a blue LED and a phosphor, an emission wavelength of the blue LED shifts to a long wavelength side with increase of temperature rise, so that there is a case where color deviation appears in the white, light emitting device.
An object of the present invention is to provide a white light emitting device having improved color rendering properties.
Furthermore, another object of the present invention is to provide a white light emitting device in which color deviation is hard to appear.